Aspirin for everyone booking by 16 weeks was associated with less severe pre-eclampsia

Design

Observational before-after cohort, single US health system

Population

Two epochs of 18,457 deliveries; aspirin 162 mg for all booking by 16 weeks

Primary outcome

Pre-eclampsia with severe features

Effect

6.9% vs 5.1%, aOR 0.65 (95% CI 0.60-0.72)

Parkland Health in Texas began dispensing 162 mg aspirin daily to every patient starting prenatal care by 16 weeks from August 2022, directly from its community clinics. Before that, aspirin was not recommended regardless of risk. The study compared two epochs of 18,457 deliveries each, excluding a six-month washout.

Pre-eclampsia with severe features fell from 6.9% to 5.1% (adjusted OR 0.65, 95% CI 0.60-0.72). The association held in people with chronic hypertension (aOR 0.72, 0.59-0.86). Abruption, postpartum haemorrhage and neonatal complications did not rise. Pharmacy records confirmed at least 80.4% of eligible patients received aspirin.

Risk-factor screening for aspirin is cumbersome and misses people. This is population-level evidence that a universal, dispensed-at-booking approach is feasible and is associated with a meaningful drop in severe disease where hypertensive disorders are common.

It is a before-after comparison in one high-risk service, so it supports considering universal aspirin in similar populations rather than proving it causes the reduction.

• Ask whether your unit's risk-factor screening actually reaches everyone eligible, or only those who remember to ask.
• Dispensing at the visit, not prescribing for later collection, is what achieved 80% uptake here.
• The dose used was 162 mg daily from before 16 weeks.
• Watch for bleeding outcomes if a universal policy is adopted; this study saw no increase.

Why it matters

It challenges the assumption that aspirin has to be targeted by risk factors to be worthwhile in a high-prevalence population.

Don't overread it

This was observational, before versus after a policy change; other changes in care over 2020-2025 could explain part of the fall.

The statistics, in plain English

An absolute fall from 6.9% to 5.1% means about 18 fewer cases of severe pre-eclampsia per 1,000 deliveries. The adjusted odds ratio of 0.65 accounts for measured differences between the two periods, but a before-after design cannot adjust for things that changed and were not measured.

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